81 GS850G Won't Rev over 4000 RPM

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  • WilliamGLX81
    #46
    What ended up happening?? I'm chasing a similar problem on my 81 650g.

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      • GS850GFan
        #47
        Originally posted by WilliamGLX81
        What ended up happening?? I'm chasing a similar problem on my 81 650g.
        Never figured it out. Took it to a mechanic, he never figured it out. Ended up selling it.

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          • tom203
            Forum Guru
            Past Site Supporter
            • Aug 2010
            • 8925
            • Norway,Maine
            #48
            Originally posted by WilliamGLX81
            What ended up happening?? I'm chasing a similar problem on my 81 650g.
            Start your own thread and folks here will have a go at it!
            1981 gs650L

            "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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              • tom203
                Forum Guru
                Past Site Supporter
                • Aug 2010
                • 8925
                • Norway,Maine
                #49
                Originally posted by GS850GFan
                Never figured it out. Took it to a mechanic, he never figured it out. Ended up selling it.
                That stinks, nice of you to respond to that inquiry. Did you get another bike?
                1981 gs650L

                "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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                  • GS850GFan
                    #50
                    Originally posted by tom203
                    That stinks, nice of you to respond to that inquiry. Did you get another bike?
                    Yeah, bought a new Indian Scout

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                      • GS850GFan
                        #51
                        Originally posted by tom203
                        Start your own thread and folks here will have a go at it!
                        I agree, start a fresh thread with as much detail as you can give and hopefully the pro's here can help you.

                        My bike would not rev with the air cleaner sides ON. With out them, it ran great. But that was the best I could do. Real bummer, I loved that machine. Seating position was perfect. PLENTY of power and the sound! Going through the gears, hearing that inline four!!!

                        DAMN IT! I might need to find a nicely sorted one....or maybe a 1000

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                          • 850 Combat
                            Forum Guru
                            Past Site Supporter
                            • Sep 2006
                            • 6018
                            • Spokane, WA, and Hampden, ME
                            #52
                            Originally posted by Brendan W
                            You are getting 12.5 V at the battery at all engine speeds? If so you have a problem. You should be getting over 14V at 5000rpm. You have either a wiring problem between the r/r or problems with the r/r itself and/or the stator. Until this is sorted you cannot be sure the ignitor is seeing the correct voltage. In my experience fixing electrical issues like this sorted a lot of other symptoms. For example poor connections to the coils themselves can be responsible for bad firing at high revs.
                            The motor is basically an air pump. If it won't rev out the first suspect is valve timing. If the chain is out by a tooth the motor suffocates at high revs. You can rev to the red line in neutral which would discount this a little but it still needs checking.
                            Motor bogging under load can also be too much air or too little fuel. The most critical place for air leaks is between the carbs and the head. Have you replaced the o-rings on that side? If you spray a bit of wd-40 in there at idle the speed can change if there is a leak.
                            I can't believe that it went to page 5 for the fact that is hasn't been charging to come out.
                            Last edited by 850 Combat; 04-25-2017, 11:44 AM.
                            sigpic Too old, too many bikes, too many cars, too many things

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                              • GS850GFan
                                #53
                                Originally posted by 850 Combat
                                I can't believe that it went to page 5 for the fact that is hasn't been charging to come out.
                                I did test the charging system and was getting good out put. Over 13+v when rev'd. Rebuilt carbs, replaced manifolds, air box boots, all clamps, air filter. Swapped out multipal jets, flow tuned. Later rebuilt the head, new head gasket, adjusted timing chain, set timing, adjusted valves, cleaned tank, replaced fuel filter and hoses, checked every spark plug for a nice blue arc.

                                It ran smooth as glass across all ranges, pulled like a train off the line, no stumbles. Just would hit a wall with the air box ends on. Took those off, ran like a dream.

                                No idea why.

                                Anyway, best of luck to those that may have this issue. I'm on to greener pastures!

                                RIDE SAVE EVERYONE!

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